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Sveriges lantbruksuniversitet www.slu.se The study area were located in Heby commune, 40 km northwest of Uppsala in Sweden. study area was on a rocky boreal forest; dominated by - Scots pine - Norway spruce - shrub species

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Sveriges lantbruksuniversitet www.slu.se Aim of study: Was to investigate the long-term effects of a single potassium (K) fertilizer in boreal forest ecosystems on 137 Cs uptake by heather and fungi 1992 – 2009, 17 year

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Sveriges lantbruksuniversitet www.slu.se Pools and processes in soil where Caesium is involved

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Sveriges lantbruksuniversitet www.slu.se, T eff (years), effective ecological half-life The ecological half-life of radiocaesium (time taken for a given activity to decrease to half of the original value) Control area: 11y for lingonberry & bilberry 9y for heather

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Sveriges lantbruksuniversitet www.slu.se Effect of K-fertilization in plants the effect was very clear for about 7 years, 1993 -2000 137 Cs activity concentration in K-fertilized are compared with the control area show a reduction with: 53% for lingonberry 63% for bilberry 69% for heather

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Sveriges lantbruksuniversitet www.slu.se Schematic view of fungi in forest soil and its connection through the mycelia with roots ≈ 10% Mycorrhizal fungi play a fundamental role in forest ecosystems and they are involved in nutrient cycling

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Sveriges lantbruksuniversitet www.slu.se Conclusion The results show that a single application of K- fertilizer (100 kg K/ha) to boreal forest plants is an effective way to decrease 137 Cs activity concen- trations in plants over a period 17 yare K-fertilizer decreased 137 Cs in heather, lingonberry and bilberry even the first year The most pronounced and significant reduction occurred over the first 7-8 years The reduction on 137 Cs in fungi after K fertilization was less pronounced, but still statistically significant